now, officials at the international atomic energy agency, which is the u.n.'s nuclear watchdog group, are also involved in this investigation and they say there are more than 100 incidents of theft regarding radioactive materials reported to their agency every single year. bret. >> casey stegal, thank you. >>> the u.n. involved in another case saying there is growing evidence that syrian president bashir al assad and senior officials have been involved in war crimes and crimes against humanity. the complex dynamics in syria have the u.s. trying to talk peace with what is literally the lesser of two evils. good evening, katherine. >> reporter: the national security council staff and the intelligence agencies are referring all questions about the u.s. government's contacts with syria to the state department where today a spokesperson tries to play down direct talks as old news. >> we've been engaging with the broad section for a long time. it's been ongoing. of course we're incredibly concerned about the terrorist threat in syria. we've made that very clear. tha